Well, I'm talking about Angels in general. Be it from the bible itself or from culture angels are written as a way for god to communicate to the common folk while still being able to remain mysterious. I hope I didn't sound condescending. I do that sometimes... :s

It is possible that Arceus could have created an angel to communicate with the humans, I could see that being the case. It would work great in terms of the legendary "Azure Flute" being...well...a legend. If it is one, that is. I'm not sure if it is acknowledged by the characters of the game or not. If the flute itself is indeed a legend, then I'd say that we could consider making the angel a fallen angel (or an angel that has watched over the planet many years).

Regardless of whether it is a legend or not, I think that an angel would fit well as the "Azure Flute"; it's well within Arceus' power and makes enough logical sense to exist, especially given the current state of the world.